A number of metallurgical converters for copper, nickel, lead or other nonferrous ores or the like, are well known in the mining art. These converters generally include those known as Peirce-Smith, Teniente, Noranda, or other similar types.
The converters which are most commonly used are basically characterized as having a cylindrical horizontal shell which can be of variable dimensions depending upon the specific production requirements. The material of construction for the shell is generally carbon steel lined with a refractory material in order to allow the converter to operate properly in contact with liquid metallic elements at temperatures of approximately 1200.degree. C. and above.
The converter is used to oxidize various components of the ores. For example, in the conversion of copper mattes, air is introduced through molten copper matte to oxidize any metal sulfides which are present. This oxidation is accomplished by injecting an oxidizing agent, most commonly air, into the molten ore bath in the converter through tuyeres which extend through the shell and refractory lining. These tuyeres are located in a predetermined arrangement usually in the bottom or lower portion of the converter shell.
During the course of operation of the converter over an extended time period, the refractory lining begins to wear or deteriorate. Usually, the refractory areas adjacent to and around the tuyeres experience the greatest wear because of the turbulence from the introduction of the air and the localized heating caused by the reaction of the air with the ore components. Also, the refractory lining can spall, crack or flake if subjected to extreme temperature fluctuations. Therefore, it becomes necessary to shut down the equipment and repair or replace the damaged refractory lining.
Previously, the usual method of repair would be to stop the operation of the converter, allow it to cool to ambient temperatures, remove the heads to facilitate entry into the shell, and replace the damaged or deteriorated portions of the refractory lining. The repair or replacement of the refractory lining is difficult and time consuming since maintenance personnel would have to work within the converter shell itself. In addition, the reliability of a refractory lining is suspect in the areas where the new or replacement lining must be joined or bonded to the remaining portions of the original lining. For this reason, it is often preferable to replace the entire refractory lining of the vessel in order to achieve longer service lives and more reliable operation when the converter is put back on stream.
Furthermore, the loss of production due to the removal of the converter from service for a considerable length of time and the repair cost (i.e. materials and labor) for installing the replacement refractory lining are relatively high. Therefore, the mining industry has long been searching for an alternative method of reliably repairing or maintaining these converters to avoid such long down time periods and high repair costs.